RSV Often Milder Than Flu in Older Adults

Respiratory Syncytial Virus (RSV) appears to cause milder illness than influenza in adults age 50 or older, according to researchers at Marshfield Clinic Research Foundation. The study, published online in Clinical Infectious Diseases, also shows RSV is a common cause of respiratory illness in older adults and that the chance of infection increases with age.

"RSV has long been known to cause serious respiratory illness in infants, but much less is known about the illnesses RSV causes in older adults," says Dr. Edward Belongia, director of the Epidemiology Research Center at Marshfield Clinic Research Foundation (MCRF). "Knowing that adults' susceptibility to RSV increases as they age is important for healthcare providers and public health officials to note as they treat and monitor respiratory illnesses this season."

RSV is a common virus that causes infections of the lungs and breathing passages. The virus is thought to cause about 10 percent of winter hospitalizations for pneumonia in adults 65 and older. Most healthy people recover from RSV in one to two weeks, but for some infants, children and older adults, RSV causes serious illness. Most children have had RSV by age 2.

Study results suggest flu may cause more severe illness than RSV in older adults. That's based on two key points:

- People with RSV delayed seeking treatment after the onset of illness more than patients with flu.

- Fewer RSV patients were hospitalized within 30 days compared to those with flu.

Symptoms of RSV are cold-like in most instances and include congested or runny nose, dry cough, low-grade fever, sore throat and headache. In severe cases, the contagious virus causes high fever, severe cough, wheezing, rapid breathing and bluish color of the skin due to lack of oxygen.

"Influenza gets a lot of attention this time of the year and for good reason it's a serious illness that affects thousands of people," says MCRF epidemiologist Maria Sundaram, one of the study's lead authors. "Although this study showed RSV may lead to fewer complications than flu, it still has the potential to cause serious respiratory illness, especially in older adults with weakened immune systems or other pre-existing conditions."

Further work is needed to understand why older adults are more susceptible to RSV than other groups, MCRF researchers said. For the study, scientists including Dr. Jennifer Meece, director of MCRF's Core Laboratory, studied nasal and throat swabs from patients age 50 and older recruited for influenza vaccine effectiveness studies from 2004-2010. MedImmune, LLC, provided funding for this study.

Source: Marshfield Clinic Research Foundation (MCRF)